This proposal requests funds to complete the construction of the Pierre Auger Observatory (PAO). The objective of the PAO is to measure, with full sky coverage, the energy, direction and composition of the cosmic rays with energies above 10^19 eV. Large aperture cosmic ray observatories are opening a new window to the universe. To address this opportunity a broad based international collaboration has come together to build a very large air shower observatory that will make an all-sky study of cosmic rays at the highest energies. A number of cosmic rays with energies near and beyond 10^20 eV have been reported. Yet neither the origin of these cosmic rays nor the acceleration mechanism responsible for their enormous energies is known. The direct search for sources as well as the behavior of the energy spectrum above 5*10^19 eV will provide important clues to these mysteries. The PAO, located in Mendoza, Argentina, has completed the engineering phase and construction is underway and is expected to be complete by about the end of 2005 and to have a 20-year lifetime.
The impact of the PAO has already gone well beyond the construction work and the capture of the first cosmic ray events. Close ties have been developed with branches of the National Technical University in Argentina where a number of students are involved, not only in building and testing equipment but in data taking tasks as well. In terms of outreach, the Visitor Center on the Auger campus has attracted more than 10,000 visitors from 26 countries. The collaboration sponsors a popular on-going lecture series for the public in the host city of Malargue and nearby communities. A particularly close relationship has been established with the people of Malargue. In the US, the PAO works closely with the CROP project based at the University of Nebraska that helps high school students install cosmic ray detectors on their schools.
